Vacuum Leak Pump and Reference Orifice Test

The first two events of the EVAP system diagnostic checks the operation of the vacuum leak pump and for a restriction in the reference orifice. With the purge solenoid and the vent solenoid both OFF, atmospheric pressure should enter the EVAP system and be detected by the FTP sensor. If atmospheric pressure is not detected, the reference orifice may be plugged. During event two, the vacuum leak pump is turned ON and the FTP sensor should indicate negative pressure within a specified value. If the pressure change is too small, a DTC P043E can set. If the pressure change is too large, a DTC P043F can set. If atmospheric pressure is measured in event one, but no negative pressure is measured in event two, an inoperative vacuum leak pump is indicated, and a DTC P2401 can set. If there is a sudden large increase in negative pressure when the pump is turned ON, a stuck on vent solenoid may be indicated and a DTC P2419 can set.